Catalyst for the dehydration reaction of hydroxypropionic acid and its derivatives, and method for producing the same.

Abstract

The present invention relates to a dehydration catalyst for hydroxypropionic acid and its derivatives, and a method for producing the same. The catalyst according to one embodiment of the present invention has high reaction yield and selectivity, and excellent lifetime characteristics.

Description

[Technical Field]

[0001] The present invention relates to a dehydration catalyst for hydroxypropionic acid and its derivatives, and a method for producing the same.

[0002] [Mutual citation of related applications] This application claims priority based on Korean Patent Application No. 10-2023-0081445 dated June 23, 2023, and all content disclosed in the said Korean Patent Application is incorporated herein as part of this specification. [Background technology]

[0003] Acrylic acid is generally synthesized through a two-step oxidation reaction of propylene, a petroleum-derived raw material. However, due to the rapid rise in crude oil prices and concerns about future depletion, research is being conducted to obtain unsaturated carboxylic acids such as acrylic acid from biomass raw materials.

[0004] Lactic acid can be mass-produced from starch through fermentation, and acrylic acid can be produced by the dehydration reaction of lactic acid. Metal phosphates, metal sulfonates, or zeolite catalysts are mainly used in the lactic acid dehydration reaction. Among these, metal phosphates have been extensively studied, but they suffer from the problem of low acrylic acid yield.

[0005] Specifically, International Publication WO2011 / 052178 states that apatite hydroxide ((Ca 10 (PO4)6(OH)2) and Sr 10 A synthetic method has been proposed to synthesize unsaturated carboxylic acids and their derivatives by dehydration reaction using (PO4)6(OH)2 as a catalyst. However, when acrylic acid is synthesized from lactic acid using apatite hydroxide, the yield of acrylic acid is only about 50-70%, and when the Ca in apatite hydroxide is replaced with Sr, 10 In the case of (PO4)6(OH)2, the yield of acrylic acid is even lower, at around 30%.

[0006] This necessitates the development of manufacturing methods and catalysts capable of synthesizing unsaturated carboxylic acids such as acrylic acid and their esters in high yield. [Overview of the project] [Problems that the invention aims to solve]

[0007] This specification aims to provide catalysts for the dehydration reaction of hydroxypropionic acid and its derivatives.

[0008] Furthermore, this specification aims to provide a method for producing a dehydration reaction catalyst for hydroxypropionic acid and its derivatives. [Means for solving the problem]

[0009] This disclosure provides a dehydration catalyst for hydroxypropionic acid and its derivatives, comprising a molded body in which primary particles of hydroxyapatite are aggregated, the volume-average particle size of the primary particles being 15 to 150 μm, and the P value represented by the following formula 1 being 3.5 to 19.

[0010] [Formula 1] P = A * B / C In the above formula 1, A is the volume-average particle size (μm) of the powder, B is the crushing strength (N) value, and C is the specific surface area (m²). 2 This is the value ( / g).

[0011] According to one embodiment, the particle size of the primary particles may be about 25 to about 100 μm.

[0012] According to one embodiment, the dehydration catalyst for hydroxypropionic acid and its derivatives may have an alkali metal content of about 3% to about 8% by weight.

[0013] According to one embodiment, the alkali metal may be sodium or potassium.

[0014] According to one embodiment, the apparent density value of the dehydration reaction catalyst of hydroxypropionic acid and its derivatives may be from about 0.8 to about 1.0 g / cm 3 and may be.

[0015] According to one embodiment, the crushing strength value of the dehydration reaction catalyst of the hydroxypropionic acid and its derivatives may be from about 6 to about 20 N.

[0016] According to one embodiment, the specific surface area value of the dehydration reaction catalyst of the hydroxypropionic acid and its derivatives may be from about 50 to 90 m 2 / g and may be.

[0017] On the other hand, the present disclosure provides a method for producing a dehydration reaction catalyst for hydroxypropionic acid and its derivatives, including the steps of adding 1 to 50 parts by weight of a binder to 100 parts by weight of hydroxyapatite to produce a slurry; molding the slurry to produce a molded body; and drying the molded body.

[0018] According to one embodiment, the binder may include 0.1 to 10 parts by weight of isopropyl alcohol with respect to 100 parts by weight of hydroxyapatite.

[0019] On the other hand, the present disclosure provides a method for producing acrylic acid, including the step of subjecting a hydroxycarboxylic acid or its derivative to a dehydration reaction in the presence of the catalyst described above.

[0020] <UNK> In the present invention, terms such as first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

[0021] Also, the terms used in this specification are used only for the purpose of explaining exemplary embodiments and are not intended to limit the present invention.

[0022] The singular expression includes plural expressions unless the context clearly indicates otherwise.

[0023] In this specification, terms such as “includes,” “equip,” or “have” are used to describe the implemented features, figures, steps, components, or combinations thereof, and do not exclude one or more other features, figures, steps, components, combinations thereof, or additions.

[0024] Furthermore, where it is referred to in this specification that each layer or element is formed "on top of" each layer or element, it means either that each layer or element is formed directly on top of each layer or element, or that other layers or elements may be formed additionally between each layer, on the object, or on the substrate.

[0025] The present invention can be modified in various ways and may take many forms; therefore, specific embodiments are illustrated and described in detail below. However, this should not be understood as limiting the present invention to any particular form of disclosure, but rather as including any modifications, equivalents, or substitutions that fall within the spirit and technical scope of the present invention.

[0026] In this specification, "hydroxypropionic acid derivative" refers to a group of compounds that encompasses hydroxypropionic acid and its derivatives, which are carboxyl acids having three carbon atoms in the main chain, with one of those carbon atoms substituted with a hydroxyl group.

[0027] Furthermore, the dehydration reaction of hydroxypropionic acid and its derivatives refers to the reaction in which the hydrogen atoms bonded to the hydroxyl group and its adjacent carbon atoms in the compound are removed (eliminated), forming a carbon-carbon unsaturated double bond.

[0028] The present invention will be described in detail below.

[0029] According to one aspect of the present invention, there is provided a molded body in which primary particles of hydroxyapatite are aggregated, the volume average particle diameter of the primary particles is 15 to 150 μm; and a dehydration reaction catalyst for hydroxypropionic acid and its derivatives, in which the P value represented by the following formula 1 is 3.5 to 19.

[0030] [Formula 1] P = A * B / C In the above formula 1, A is the value of the volume average particle diameter (μm) of the powder, B is the value of the crushing strength (N), and C is the specific surface area (m 2 0[ / g) value.

[0031] The apatite compound means a compound having an apatite structure, usually containing calcium and phosphorus, and means a calcium phosphate-based compound represented by the chemical formula of Ca A (PO4) B -X form.

[0032] 2[ / ID=22] Among these, hydroxyapatite means a compound in which X is a hydroxy group in the above chemical formula. Such a hydroxyapatite compound can be used as a catalyst in the dehydration reaction of hydroxypropionic acid and its derivatives for the production of unsaturated carboxylic acids due to its unique structure and the presence of acid sites.

[0033] However, when such a calcium phosphate-based compound is used as a general hydroxyapatite single-phase catalyst, the yield is not high in the dehydration reaction, and in particular, there are problems such as a significant decrease in the yield as the reaction time elapses, a very short lifespan, and low processability.

[0034] The inventors of the present invention have discovered that, in methods for producing acrylic acid and the like by the dehydration reaction of hydroxypropionic acid and its derivatives using hydroxyapatite as a catalyst, when a molded body is used as a catalyst by molding hydroxyapatite powder, adjusting the particle size of the hydroxyapatite powder used for molding to a certain range can provide a catalyst with high reaction yield and selectivity, as well as excellent lifetime characteristics, thus completing the present invention.

[0035] According to one embodiment of the present invention, a dehydration catalyst for hydroxypropionic acid and its derivatives is provided, comprising a molded body in which primary particles of hydroxyapatite are aggregated, wherein the volume-average particle size of the primary particles is 15 to 150 μm, and the P value represented by the following formula 1 is 3.5 to 19.

[0036] [Formula 1] P = A * B / C In the above formula 1, A is the volume-average particle size (μm) of the powder, B is the crushing strength (N) value, and C is the specific surface area (m²). 2 This is the value ( / g).

[0037] According to one embodiment, the volume-average particle size of the primary particles may be about 15 to about 150 μm.

[0038] In other words, instead of using hydroxyapatite as a crystalline compound itself or its powder in its original state as a catalyst, a molded body formed from the powder is used as a catalyst. In this case, the particle size of the powder constituting the molded body, i.e., the primary particles, may be approximately 15 to approximately 150 μm, or approximately 15 μm or more, or approximately 17 μm or more, or approximately 20 μm or more, or approximately 23 μm or more, or approximately 25 μm or more, or approximately 150 μm or less, or approximately 140 μm or less, or approximately 130 μm or less, or approximately 120 μm or less, or approximately 110 μm or less, or approximately 100 μm or less.

[0039] If the size of the primary particles used to manufacture the molded catalyst, i.e., the hydroxyapatite powder, is excessively small, the density of the powder within the catalyst molded body tends to increase, leading to increased physical strength. However, this characteristic can cause problems such as a decrease in the specific surface area required for the dehydration reaction. If the size of the primary particles, i.e., the hydroxyapatite powder, is excessively large, the strength of the catalyst molded body becomes weak, making molding impossible, and problems such as side reactions due to catalyst crushing and increased differential pressure in the reactor may occur during the dehydration reaction.

[0040] According to one embodiment, the dehydration catalyst for hydroxypropionic acid and its derivatives may have an alkali metal content of about 3% to about 8% by weight.

[0041] In hydroxyapatite compounds used as catalysts for the production of unsaturated carboxylic acids or their derivatives, the alkali metal content within the compound can affect the selectivity during the production of unsaturated carboxylic acids and their derivatives. Specifically, a low alkali metal content in the catalyst, particularly on the catalyst surface, results in low selectivity, while a high alkali metal content can maintain high selectivity.

[0042] On the other hand, the molar ratio of calcium to phosphorus on the catalyst surface (Ca / P molar ratio) affects the product yield, i.e., the acrylic acid conversion rate. If the Ca / P molar ratio is excessively high or excessively low, the yield may decrease.

[0043] However, during the production of unsaturated carboxylic acids or their derivatives, selectivity and conversion rate exhibit a trade-off relationship, making it difficult to improve both simultaneously.

[0044] According to one embodiment of the present invention, the alkali metal content in the catalyst can be maintained at a high level of approximately 3% to 8% by weight, and the alkali metal content on the catalyst surface can also be maintained at a high level. This makes it possible to further improve the selectivity and conversion rate during the production of unsaturated carboxylic acids and their derivatives by increasing the alkali metal content on the catalyst surface and controlling the mixing ratio with Ca and P.

[0045] Specifically, in a catalyst according to one embodiment, the molar ratio of calcium to phosphorus (P) on the catalyst surface (Ca / P molar ratio) may be about 1.0 or more and about 1.2 or less. More specifically, it may be about 1.0 or more, or about 1.05 or more, or about 1.1 or more, and may be about 1.2 or less, or less than about 1.2, or about 1.15 or less.

[0046] Furthermore, the total molar ratio of calcium and alkali metals to phosphorus on the catalyst surface ((Ca+M) / P molar ratio) may be approximately 1.2 or more and approximately 1.6 or less. More specifically, it may be approximately 1.2 or more, or approximately 1.3 or more, and approximately 1.6 or less, or less than approximately 1.6, or approximately 1.5 or less, or approximately 1.45 or less, or approximately 1.4 or less.

[0047] The catalyst may have a high alkali metal content on its surface, based on the total weight of elements present on the catalyst surface, ranging from approximately 4% by weight to approximately 8% by weight. More specifically, it may be approximately 4% by weight or more, or approximately 5% by weight or more, or approximately 6% by weight or more, or approximately 6.5% by weight or more, and approximately 8% by weight or less, or approximately 7.5% by weight or less, or approximately 7% by weight or less.

[0048] On the other hand, in the present invention, the atomic weight reference element content (atomic %) of elements including phosphorus, calcium, and alkali metals on the catalyst surface can be measured by XPS analysis.

[0049] From the calcium (Ca) content (at%), phosphorus (P) elemental content (at%), and alkali metal (M) elemental content (at%) calculated by the aforementioned XPS analysis, the molar ratio of calcium to phosphorus on the catalyst surface can be determined from the ratio of Ca elemental content (Ca at%) to P elemental content (P at%). Furthermore, the total molar ratio of calcium and alkali metal to phosphorus can be determined from the ratio of (Ca at% + M at%) / (P at%).

[0050] Furthermore, the alkali metal content (weight %) present on the catalyst surface can be calculated from the elemental content (at %) calculated above.

[0051] As described above, by controlling the content ratio of phosphorus, calcium, and alkali metals on the catalyst surface and the content of the elements within the catalyst, the selectivity and conversion rate during the production of unsaturated carboxylic acids or their derivatives can be further improved.

[0052] Specifically, the alkali metal content in the catalyst may be approximately 3% by weight or more and approximately 5% by weight or less based on the total weight of the catalyst. More specifically, the alkali metal content in the catalyst may be approximately 3% by weight or more, or approximately 3.2% by weight or more, and approximately 5% by weight or less, or approximately 4.5% by weight or less, or approximately 4% by weight or less, or approximately 3.7% by weight or less, based on the total weight of the catalyst.

[0053] Furthermore, the molar ratio of calcium to phosphorus in the catalyst (Ca / P molar ratio) may be approximately 1.3 or more and approximately 1.5 or less. More specifically, it may be approximately 1.3 or more, or approximately 1.35 or more, or approximately 1.4 or more, and may be approximately 1.5 or less, or approximately 1.45 or less.

[0054] The total molar ratio of calcium and alkali metal (M) to phosphorus in the catalyst ((Ca+M) / P molar ratio) may be approximately 1.2 or more and approximately 2 or less. More specifically, it may be approximately 1.2 or more, or approximately 1.5 or more, or approximately 1.6 or more, or approximately 1.65 or more, or approximately 1.7 or more, and may be approximately 2 or less, or approximately 1.9 or less, or approximately 1.8 or less, or approximately 1.75 or less.

[0055] On the other hand, in the present invention, the content of elements including phosphorus, calcium, and alkali metals in the catalyst can be calculated by inductively coupled plasma analysis (ICP), or more specifically, inductively coupled plasma atomic emission spectrometry (ICP-OES).

[0056] According to one embodiment, the alkali metal may be sodium or potassium, and sodium is preferred considering its superior improvement effect.

[0057] As described above, the catalyst according to the present invention can simultaneously achieve high selectivity and high conversion rates during the production of unsaturated carboxylic acids or their derivatives by controlling the content ratio of phosphorus, calcium, and alkali metals on the catalyst surface and the entire surface within an optimal range.

[0058] According to one embodiment, the apparent density of the dehydration catalyst for hydroxypropionic acid and its derivatives is approximately 0.8 to approximately 1.0 g / cm³. 3 This may also be the case. If the density is excessively low, the catalyst strength may be weak, and side reactions may occur due to catalyst crushing during the dehydration reaction, which can lead to problems such as an increase in differential pressure inside the reactor. If the density is excessively high, problems such as a decrease in specific surface area may occur.

[0059] According to one embodiment, the crushing strength value of the dehydration reaction catalyst for hydroxypropionic acid and its derivatives may be about 6 to about 20 N. In other words, the catalyst according to one embodiment of the present invention has an excellent crushing strength value and is not easily crushed even when exposed to harsh reaction conditions while packed inside the reactor, so that its packed state can be maintained in its initial form.

[0060] According to one embodiment, the specific surface area of ​​the dehydration reaction catalyst for hydroxypropionic acid and its derivatives is approximately 50 to approximately 90 m². 2 / g, or approximately 50m 2 / g or more, or approximately 55m 2 / g or more, or approximately 60m 2 / g or more, approximately 90m 2 Less than / g, or approximately 85m 2 It is less than / g and can have a large non-surface area.

[0061] Furthermore, the dehydration catalyst for hydroxypropionic acid and its derivatives may have a P value of approximately 3.5 to approximately 19, represented by the following formula 1, which may be approximately 3.5 or more, or approximately 4.0 or more, or approximately 5.0 or more, or 6.0 or more, or approximately 19 or less, or approximately 17 or less, or approximately 15 or less, or approximately 12 or less, or approximately 10 or less.

[0062] [Formula 1] P = A * B / C In the above formula 1, A is the volume-average particle size (μm) of the powder, B is the crushing strength (N) value, and C is the specific surface area (m²). 2 This is the value ( / g).

[0063] The aforementioned equation 1 parameterizes factors that can directly affect the strength of a catalyst in a form formed from primary particle powder. If the parameter values ​​are excessively large or excessively small, the catalyst deactivation time will be shortened, which can lead to problems such as a decrease in catalyst performance and reduced long-term stability.

[0064] Furthermore, according to another aspect of the invention, a method for producing a dehydration reaction catalyst for hydroxypropionic acid and its derivatives is provided, comprising the steps of: preparing a slurry by adding 1 to 50 parts by weight of a binder to 100 parts by weight of hydroxyapatite; forming the slurry to produce a molded body; and drying the molded body.

[0065] According to one embodiment, the manufacturing method may further include a step of grinding the hydroxyapatite prior to adding the binder.

[0066] For grinding, it is preferable to use a milling machine such as a jet mill or pin mill, as this allows for adjustment of the particle size of the resulting pulverized powder, that is, the volume-average particle size of the primary particles.

[0067] The binder may contain a water or alcohol-based solvent (excluding isopropyl alcohol) and isopropyl alcohol, which is a binder component.

[0068] According to one embodiment, the binder can be used in an amount of about 1 part by weight or more, or about 5 parts by weight or more, or about 10 parts by weight or more, and about 70 parts by weight or less, or about 60 parts by weight or less, or about 50 parts by weight or less, per 100 parts by weight of hydroxyapatite.

[0069] If the amount of the aforementioned binder used is excessively small or excessively large, the moldability during catalyst manufacturing may decrease, which can lead to problems such as a decrease in the strength of the manufactured catalyst.

[0070] However, the binder content may vary depending on the particle size, drying temperature, drying time, and other molding conditions.

[0071] The binder may contain approximately 0.1 parts by weight or more, or approximately 1 part by weight or more, or approximately 3 parts by weight or more, and approximately 10 parts by weight or less, or approximately 9 parts by weight or less, or approximately 8 parts by weight or less of isopropyl alcohol.

[0072] If the isopropyl alcohol content is too low or too high, problems may arise such as a decrease in the strength of the catalyst produced or a reduction in its specific surface area.

[0073] In the step of adding a binder to hydroxyapatite powder and then mixing to produce a slurry, the mixing method is not particularly limited.

[0074] Furthermore, when molding a slurry to produce a molded product, a molding method using an extruder or the like is preferred.

[0075] Subsequently, the molded bodies, which have been formed into pellets or other forms, are dried. In the drying step, drying can be carried out for about 30 minutes to about 24 hours under conditions of approximately 10°C or above, or approximately 20°C or above, and approximately 120°C or below, or approximately 110°C or below.

[0076] According to one embodiment, the step of calcining the dried catalyst may further be included.

[0077] On the other hand, this disclosure provides a method for producing acrylic acid, comprising the step of dehydrating a hydroxycarboxylic acid or a derivative thereof in the presence of the aforementioned catalyst.

[0078] On the other hand, this specification provides a method for producing unsaturated carboxylic acids and their derivatives using the catalyst.

[0079] Specifically, the manufacturing method includes the step of dehydrating a hydroxycarboxylic acid or its derivative in the presence of a catalyst for producing the unsaturated carboxylic acid or its derivative.

[0080] In the method for producing unsaturated carboxylic acids and their derivatives according to the present invention, specific examples of hydroxycarboxylic acids used as raw materials include lactic acid, citric acid, 3-hydroxypropionic acid, 3-hydroxy-2-methylpropionic acid, 3-hydroxybutanoic acid, 3-hydroxy-2-methylbutanoic acid, or 2,3-dimethyl-3-hydroxybutanoic acid, and derivatives such as salts, esters, or dimers of these can be used.

[0081] The hydroxycarboxylic acid or its derivative may be used in an aqueous solution in water, or in a solution in a mixed solvent obtained by mixing water with a hydrophilic organic solvent such as alcohol or ether.

[0082] At this time, the concentration of the hydroxycarboxylic acid or its derivative is not particularly limited, but may be 20% by weight or more and 60% by weight or less, taking efficiency into consideration.

[0083] Furthermore, the amount of catalyst used during the dehydration reaction can be appropriately selected considering the type of reactant, reaction time, etc. For example, hydroxycarboxylic acid or its derivative can be added at a rate of 0.05 g or more and 3 g or less per hour per 1 g of catalyst, more specifically, at a rate of 0.1 g or more and 1 g or less per hour, or at a rate of 0.5 g per hour.

[0084] Furthermore, the dehydration reaction may be carried out as a continuous reaction using a fixed-bed reactor or as a batch reaction. More specifically, it may be carried out as a continuous reaction in which the catalyst is packed into a fixed-bed reactor and the reactants are continuously supplied to the reactor to carry out the reaction, thereby continuously producing the product.

[0085] During a continuous reaction using the fixed-bed reactor described above, inert gases such as nitrogen, argon, and helium can be used as carrier gases. The amount of carrier gas to be introduced is not particularly limited and can be appropriately determined depending on the reaction conditions, such as the amount of reactants introduced. For example, the carrier gas may be introduced at a rate of 5 ml / min or more and 500 ml / min or less per gram of catalyst.

[0086] Furthermore, the dehydration reaction may be carried out at a temperature of 300°C to 500°C. More specifically, it may be carried out at a temperature of 300°C or higher, or 350°C or higher, or 360°C or higher, and 500°C or lower, or 450°C or lower, or 380°C or lower.

[0087] Furthermore, the dehydration reaction may be carried out at a pressure of 0.5 bar or more and 5 bar or less. More specifically, it may be at a pressure of 0.5 bar or more, or 0.8 bar or more, and 5 bar or less, or 2 bar or less, and even more specifically, it may be carried out under atmospheric pressure (1 ± 0.2 bar) conditions.

[0088] Furthermore, the reactant, hydroxycarboxylic acid or its derivative, is 0.05h -1 More than 3 hours -1 It can be introduced at the following Weight-Hour Space Velocity (WHSV). More specifically, 0.05h -1 More than or equal to 0.1h -1 Above, or 0.3h -1 That's all, and 3 hours -1 The following, or 1 hour -1 The following or 0.8h -1 It can be deployed at the following WHSV speeds.

[0089] The reaction temperature exceeds 500°C, the reaction pressure is less than 0.5 bar, or the reactant feed rate WHSV is 0.1 h. -1 If the reaction temperature is below 300°C, the catalytic activity may increase excessively, potentially leading to hydrogenocratic side reactions and consequently reducing selectivity. On the other hand, if the reaction temperature is below 300°C, the reaction pressure exceeds 5 bar, or the reactant feed rate WHSV is 1 h -1 If the reaction rate exceeds a certain threshold, the conversion rate decreases, requiring other reaction conditions to be made more stringent. This can shorten the catalyst life and potentially increase costs during the product separation and recovery stage.

[0090] As a result of the dehydration reaction described above, at least a portion of the hydroxycarboxylic acid or its derivatives will be converted into an unsaturated carboxylic acid or its derivatives.

[0091] The method for producing an unsaturated carboxylic acid or its derivative according to the present invention, by using the catalyst described above, improves the conversion rate to unsaturated carboxylic acid and enables the production of unsaturated carboxylic acid and its derivative in high yield. [Effects of the Invention]

[0092] The catalyst according to one embodiment of the present invention exhibits high reaction yield and selectivity, as well as excellent lifetime characteristics. [Modes for carrying out the invention]

[0093] The operation and effects of the invention will be described in more detail below through specific embodiments of the invention. However, these embodiments are presented merely as examples of the invention and do not determine the scope of the invention's rights.

[0094] <Examples> (Catalyst manufacturing) (Example 1) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0095] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0096] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to have a volume-average particle size of approximately 26 μm.

[0097] To 100 parts by weight of the obtained particles, 28 parts by weight of water and 5 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 60°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0098] (Example 2) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0099] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0100] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to have a volume-average particle size of approximately 42 μm.

[0101] To 100 parts by weight of the obtained particles, 28 parts by weight of water and 5 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 60°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0102] (Example 3) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0103] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0104] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to have a volume-average particle size of approximately 60 μm.

[0105] To 100 parts by weight of the obtained particles, 25 parts by weight of water and 5 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 30°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0106] (Example 4) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0107] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0108] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to have a volume-average particle size of approximately 80 μm.

[0109] To 100 parts by weight of the obtained particles, 35 parts by weight of water and 5 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 100°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0110] (Example 5) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0111] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0112] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to have a volume-average particle size of approximately 90 μm.

[0113] To 100 parts by weight of the obtained particles, 28 parts by weight of water and 5 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 70°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0114] (Comparative Example 1) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0115] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0116] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to have a volume-average particle size of approximately 12 μm.

[0117] To 100 parts by weight of the obtained particles, 28 parts by weight of water and 5 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 120°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0118] (Comparative Example 2) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0119] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0120] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to have a volume-average particle size of approximately 8 μm.

[0121] To 100 parts by weight of the obtained particles, 28 parts by weight of water and 5 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 60°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0122] (Comparative Example 3) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0123] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0124] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to be approximately 160 μm in volume-average size.

[0125] To 100 parts by weight of the obtained particles, 28 parts by weight of water and 10 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 60°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0126] (Comparative Example 4) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0127] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0128] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to be approximately 220 μm in volume-average size.

[0129] To 100 parts by weight of the obtained particles, 35 parts by weight of water was added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder. The pellets were dried at approximately 150°C for approximately 12 hours to obtain a catalyst molded body in the form of solid pellets.

[0130] (Comparative Example 5) 35g of HAP and 65g of CaPP were mixed and placed in a high-temperature, high-pressure reactor. Then, 500ml of 1M NaOH solution was added, and the reaction was carried out at 150°C and 5atm for 4 hours. The resulting white precipitate was filtered and washed to obtain a powdered Na-HAP component catalyst (yield: 90%).

[0131] The catalyst in powder form obtained above was finely ground using a jet mill or pin mill. During grinding, the particle size of the produced particles was adjusted by changing the milling machine conditions.

[0132] Using a wet-type PSD (Particle Size Distribution) analysis system (Microtrac S3500), the particle size was measured to be approximately 500 μm in volume-average size.

[0133] To 100 parts by weight of the obtained particles, 25 parts by weight of water and 8 parts by weight of isopropyl alcohol were added as a binder and thoroughly mixed. Then, pellets approximately 2.5 mm in size were produced using an extruder, but the molding process failed.

[0134] (Measurement of crushing strength) The crushing strength of a single pellet was measured using a strength measuring instrument, according to the ASTM D4179 standard.

[0135] (Density measurement) The tap density was measured using a COPLEY tap density tester, with the number of taps kept the same.

[0136] (Measurement of specific surface area) Using BELSORP-mino II from BEL Japan, the specific surface area of ​​the catalyst was calculated from the amount of nitrogen gas adsorbed under liquid nitrogen temperature (77K).

[0137] (Progression of the dehydration reaction of lactic acid) Approximately 0.71 g of the catalyst produced in Production Example 1 was packed into a fixed-bed reactor, and a 30 wt% aqueous solution of lactic acid was added under normal conditions of a reaction temperature of 370°C and atmospheric pressure (1 ± 0.2 bar) for 0.67 hW.-1 The dehydration reaction was carried out by supplying the water.

[0138] During the initial 4 hours of the reaction, the reaction was stabilized by receiving and removing the reactants. After that, the reaction was carried out continuously for 2 hours, while the resulting liquid product was collected as a liquid sample using a 4°C cooling collector.

[0139] The acrylic acid recovery rate was monitored, and after confirming that the reaction had been activated by identifying the point where the recovery rate reached its maximum value, the catalyst deactivation time was measured as the point at which the recovery rate decreased by 10% relative to the baseline, using 24 hours later as the reference point.

[0140] The measurement results are summarized in the table below.

[0141] [Table 1]

[0142] Referring to the table above, in some comparative examples, the deactivation time was reached to a certain extent, but in these cases, the strength decreased significantly. When the catalyst's crushing strength is low, as in these comparative examples, the catalyst molded body located beneath the catalyst packed bed, which is subjected to high loads as the reaction progresses, collapses, and as a result the catalyst packed bed cannot maintain its shape, impairing the long-term stability of the reaction.

[0143] However, the catalyst according to the embodiment of the present invention has a large specific surface area and very high crushing strength, and it can be confirmed that it has excellent long-term stability, which can be estimated by the deactivation time.

Claims

1. The material contains a molded body in which primary particles of hydroxyapatite are aggregated. The volume-average particle size of the primary particles is 15 to 150 μm; A dehydration catalyst for hydroxypropionic acid and its derivatives, having a P value of 3.5 to 19, as expressed in Formula 1 below. [Formula 1] P = A * B / C In the above formula 1, A is the volume-average particle size (μm) of the powder, B is the crushing strength (N) value, and C is the specific surface area (m²). 2 This is the value per g.

2. The volume-average particle size of the primary particles is 25 to 100 μm. A catalyst for the dehydration reaction of hydroxypropionic acid and its derivatives according to claim 1.

3. The alkali metal content is 3% to 8% by weight. A catalyst for the dehydration reaction of hydroxypropionic acid and its derivatives according to claim 1.

4. The catalyst for the dehydration reaction of hydroxypropionic acid and its derivatives according to claim 3, wherein the alkali metal is sodium or potassium.

5. The apparent density is 0.8 to 1.0 g / cm³. 3 The catalyst for the dehydration reaction of hydroxypropionic acid and its derivatives according to claim 1.

6. A dehydration catalyst for hydroxypropionic acid and its derivatives according to claim 1, wherein the crushing strength value is 6 to 20 N.

7. The specific surface area value is 50 to 90 m². 2 A dehydration catalyst for hydroxypropionic acid and its derivatives according to claim 1, wherein the amount is / g.

8. A step of preparing a slurry by adding 1 to 50 parts by weight of a binder to 100 parts by weight of hydroxyapatite; A step of molding the slurry to produce a molded body; and A method for producing a dehydration catalyst for hydroxypropionic acid and its derivatives, comprising the step of drying the molded body.

9. The method for producing a dehydration catalyst for hydroxypropionic acid and its derivatives according to claim 8, wherein the binder comprises 0.1 to 10 parts by weight of isopropyl alcohol per 100 parts by weight of hydroxyapatite.

10. A method for producing acrylic acid, comprising the step of dehydrating a hydroxycarboxylic acid or a derivative thereof in the presence of the catalyst described in claim 1.

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